Apple's announcement to ditch the graphics chips designed by Imagination Technologies (IMG) and the subsequent share price collapse that followed could leave the door open for the U.S. giant to acquire the British firm, investment bank Jefferies said in a note on Tuesday.

Imagination Technologies design graphics processing units (GPU), which are key components in Apple products allowing high-quality images on its retina displays. Apple on Monday said that it's developing its own "independent graphics design" and will be "reducing its future reliance on Imagination's technology" over the next 15 to 24 months.

Shares of the U.K. company plunged on Monday closing at £1.03 ($1.28), down from Friday's close of £2.68. Apple is Imagination's largest customer. Investec said in a note on Monday that it had expected Apple to account for around 50 to 60 percent of the group's sales this year.

One theory about why Apple made the move is that it eventually wants to acquire Imagination for its key PowerVR GPU.

"A Byzantine analysis would have Apple intent on taking over Imagination for PowerVR, and using the warning of cessation to depress its prey's valuation (and emphasize its dependence on Apple) before pouncing. A version of this would see Apple standing by to acquire IMG's IP (intellectual property) in any future crisis – perhaps at least providing a safety net to value," Jefferies said in a note.

"This seems a long shot," the research added.

Apple declined to comment on this when contacted by CNBC.

Jefferies downgraded its outlook on Imagination's stock from "buy" to "hold" and put a 95 pence price target on it, which represents a further fall from Monday's close.

Apple is Imagination's fourth-largest shareholder with a stake of just over 8 percent, according to regulatory filings, and the Cupertino-based titan certainly has enough cash to make an acquisition. Last year, Apple confirmed that it was in talks to acquire Imagination but did not make an offer, showing that it was interested.

Credit Suisse on Tuesday upgraded Imagination from "underperform" to "neutral" with a £1 price target, down from £1.80 on the prospect of an acquisition. The investment bank said it sees the likelihood of some interest in the company's assets in graphics technology with the increased probability of mergers and acquisitions especially from China.

But the iPhone maker has also hired key players from Imagination and other chip companies as it strives to get a tighter hold on its supply chain, which could give it the expertise it needs to go it alone. Another theory behind the clash of the two companies is that it's actually a bargaining tactic.

Jefferies said Apple could be playing the role of "bargaining bully" to get the lowest royalty rate it can.

Michaela Rehle | Reuters

"How low would presumably be set by whatever can keep IMG on life support – not a happy picture, unless IMG actually has strong IP and Apple is bluffing," Jefferies said.

Another scenario sees a fierce legal battle between Apple and Imagination, with the latter saying it doubts its biggest customer would be able to create the technology in-house without infringing patents. This would be "expensive and difficult" for Imagination, Jefferies said.

"IMG may be able to fight on patents, or this may be a bargaining move. In the worst case, survival, let alone value, is in question," the note said.

Analysts seem major risks for the business ahead. Apple accounted for £60.7 million of Imagination's sales in fiscal 2016, and it expects it to represent around £65 million of sales in fiscal 2017.

"Going forwards, the loss of this revenue stream will have a material impact on the financials of the company - while we would expect there will be some areas where cost reductions will be possible, Imagination will still need to invest in its IP roadmap to support its other customers," Investec said, adding that as Apple walks away, it could raise the risk of other customers not signing future licenses.